Over 50 % of drug leaving a metered dose inhaler (MDI) never reaches the patient and instead is deposited with in the pacer. There is also a very high degree of dependence of drug delivery on the combination of drug/spacer/patient factors. Detailed understanding drug delivery. The overall goal of the proposed study is to design, fabricate and test an improved pediatric spacer with optimal drug delivery patterns. During Phase I a sophisticated CFD analysis was used in combination with in-vitro experiments to identify specific design characteristics favorable/(un) favorable for overall drug delivery. Based upon the simulations a novel spacer was designed which used purely geometrical changes that (a) reduced drug deposition in spacer (b) increased emitted drug in the respirable range (c) lowered velocity of the emitted drug. The improved performance was confirmed through in-vitro experimental comparisons between the prototype spacer and several commercial spacers. In Phase II, the CFDRC spacer design will be further optimized using more advanced computational techniques, followed by manufacture of prototypes for more sophisticated and rigorous bench-top testing, clinical tests of the fully optimized spacer, and preparation for Phase Ill commercialization. PROPOSED COMMERCIAL APPLICATIONS: The improved design(s) developed in this study will have a direct impact on the 40-50 million asthma/allergy patients in the U.S. alone. DHD HealthCare and ARC medical have already expressed their interest in manufacturing/marketing the CFDRC spacer in the multi-million dollar respiratory care devices market.